The present invention relates to reel-tension motor drive systems in general, and more particularly to such a system for rolling mills, paper manufacturing, etc.
A reel-tension motor drive system generally includes a pay-off reel, a winding reel, one unloading the other in the process, with or without intermediary treatment of the unrolled material, which can be a metal strip passed on a rolling mill, or a paper strip to be processed.
Reel drives involve in general a regulator system in order to maximize the transfer operation of material from one reel to the other without exceeding the permissible tension in the strip in between. This kind of regulation accommodates accelerations and decelerations as can be required with a rolling mill operation, and maintains maximum speed between the extreme conditions from maximum coil diameter to minimum coil diameter in one reel.
Other factors involved are the inertia to be compensated for and the nature of the material which imposes a maximum torque reel and a maximum tension.
A reel-tension system will generally require control circuitry containing references such as run speed, tension, strip velocity, the direction of winding and the coil diameter which is determining inertia compensation on one or the other reel.
One important factor is tracking continuously the coil diameter in order to regulate for the correct tension and provide inertia compensation signals during acceleration or deceleration periods.
It has been the practice until now to use two separate strip velocity signals, one on the entry side, the other on the delivery side of the reel-tension system, and to perform calculations leading to the knowledge of the coil diameters of the pay-off reel and of the rewind reel, respectively.